BACKGROUND: Optimal care for frail elderly patients depends on comprehensive assessment. This is especially true in the complex setting of interdisciplinary home care programs. To facilitate comprehensive assessment, as well as to generate a useful, policy-relevant patient database, standardized, multidimensional, and validated instruments are very helpful. OBJECTIVES: The aim of the present study was to demonstrate that the Minimum Data Set assessment instrument for Home Care (MDS-HC) can be used to detect functional and cognitive impairment as defined by analogous research instruments. RESEARCH DESIGN: This was a cross-sectional correlation study. SUBJECTS: We studied 95 patients admitted to home care services of the Health Care Agency of Bergamo (Italy). MEASURES: The MDS-HC form was completed for all patients by well-trained nurses, independently of and with nurses blinded to the results from the research rating scales. The Barthel Activities of Daily Living (ADL) Index, the Instrumental Activities of Daily Living of Lawton (IADL), and the Mini Mental State Examination (MMSE) were considered the gold standard. RESULTS: Agreement between the MDS-HC scales and the research rating scales was assessed with Pearson's correlation coefficient. This coefficient was 0.74 for MDS-ADL versus Barthel Index, 0.81 for MDS-IADL versus Lawton Index, and 0.81 for Cognitive Performance Scale versus MMSE, indicating an excellent agreement. CONCLUSIONS: The MDS-HC scales, when performed by trained nurses using recommended protocols, provide a valid measure of function and cognitive status in frail home care patients. These findings point out the overall validity of the functional and clinical data contained in the MDS-HC assessment. Use of the MDS-HC gives the unique opportunity of setting up a database, a prerequisite for all epidemiological evidence-based medicine studies.